When do you use the plural possessive of months?

Answer 1

The plural possessive (an inanimate possessive) is months' and it is used when the condition or action is one that occurs in more than one month, or following a period of months. It is often replaced by the word month as a noun adjunct, or by using a preposition.

Example:

The two months' supply of pills was used up in three weeks.

(His two-month supply of pills was used up in three weeks.)

Three months' work on the bridge cost over a million dollars.

(Three months of work on the bridge cost over a million dollars.)

The months' names in English come from the Roman calendar.

(The month names in English come from the Roman calendar.)

Answer 2

You use the plural possessive form of months when you are referring to a specific range of months belonging to someone or something. For example, "The team's meetings are scheduled for January's and February's agendas."